Spin made in Austria The Isospeed Black Fire spin string increases twist in your power shots. The spin version of the notorious Black Fire makes your game even more aggressive. Due to its six-sided cross section, the Isospeed top seller not only gives the ball hellish acceleration but catapults it in an accurate arc to the line. This string offers ultimate control and an extra fine sensitivity. The innovative pre-stretching, liquid waxing and double heating make the Austrian mono-filament polyester string the High End String which many supporters of the professional tour have. Be sure to get the special twist: Isospeed Black Fire S Highlights: spin-friendly power string for professionals and experienced players reduced tension loss due to pre-stretching process wax refinement reduces abrasion absolute evenness due to the second heating process designed for the most demanding players